1. Field of the Invention
The present disclosure relates to a multi-type wind turbine having a plurality of unit generators in one tower.
2. Description of the Related Art
Wind power generation refers to a generation method of converting energy generated by wind into mechanical energy (rotational force) through a spindle using a windmill, and allowing the mechanical energy to drive a generator, thereby obtaining electrical power converted into electrical energy.
Wind power generation has the highest economic efficiency among energy sources that have been developed up to the present as well as provides an advantage capable of generating electricity using wind which is a clean energy source with no cost for an indefinite period of time, and thus active investment has been made by American, Asian as well as European developers.
The foregoing wind turbine for wind power generation may be divided into a vertical shaft wind turbine and a horizontal shaft wind turbine according to the direction of the rotation shaft. Up to now, the horizontal shaft wind turbine has high efficiency and stable performance compared to the vertical shaft wind turbine, and therefore, the horizontal shaft wind turbine has been mostly applied to the commercial wind power complex.
In order to obtain more power, a typical horizontal type wind generator should have an increased size of blade or should be mounted with a generator having a capacity corresponding to the size of the blade. However, as increasing the size of the blade or increasing the capacity of the generator, the weight of the generator may be increased and thus the scale of the tower and structure for supporting such a heavy blade and generator should be also increased. As a result, when a power generation facility including the blade and generator is increased in weight, the weight of components such as bearings for supporting the weight should be also increased, and a separate particular device for a yaw operation should be installed to rotate the direction of a rotary blade according to the direction of wind.
Due to this, the installation and maintenance cost increases by geometric progression, thereby resulting in a problem of causing a significant obstacle in the broad distribution of wind turbines due to an increase of technical degree of difficulty and cost.
Taking this into consideration, in recent years, a multi-type wind turbine in which a plurality of generator units are disposed along a circumferential direction around one tower as illustrated in FIG. 1 has been known. For the multi-type wind turbine, one main nacelle 2 is installed for one tower 1, and a plurality of support arms 3 are rotatably combined with the main nacelle 2 in a radial direction, and a unit generator (G) is installed for each of the support arms 3, respectively. The unit generator (G) may include a sub-nacelle 4 including a generator (not shown), a rotor (not shown) rotatably combined with the sub-nacelle 4, and a small-sized blade 5 combined with the rotor to be rotated together with the rotor.
The foregoing multi-type wind turbine may increase the number of unit generators (G) without increasing the size of the blade 5 to obtain a lot of power, and thus it is not required to excessively increase the scale of the tower 1 and structure since the weight of the blade 5 is not excessively increased, and as a result, the size of components such as bearings for supporting each unit generator (G) may not be increased, thereby reducing the installation and maintenance cost.
However, though having the above advantages, according to the forgoing multi-type wind turbine in the related art, as the support arm 3 is rotated with respect to the main nacelle 2, the variation of wind speed is terrible, the noise is aggravated, and the fatigue load of a system is increased as well as the structural strength of the support arm 3 is weakened, thereby resulting in a problem that it cannot be applicable to a large capacity of unit generator (G).
Furthermore, according to a multi-type wind turbine in the related art, each unit generator (G) is disposed in a downwind format at a front surface of the tower 1 and thus it may be difficult to maintain a gap (t1) between a blade edge of each blade 5 and the tower 1, thereby resulting in that the blade 5 can be damaged and collided with the tower 1.
In addition, according to a multi-type wind turbine in the related art, the weight of one blade is significant and thus a lot of energy should be consumed to control the angle of each blade according to the wind conditions as well as the reaction speed is slow, and the aerodynamic performance is decreased to reduce the amount of energy production as the vicinity of a blade root is formed in a cylindrical shape, and the speed at a blade edge should be increased in order to enhance the amount of energy production, thereby increasing the noise.